*{
    padding: 0;
    margin: 0;
    box-sizing: border-box;
}
.box{
    margin: 50px auto;
    width: 500px;
    height: 500px;
}
button{
    width: 40px;
}
th,td{
    width: 100px;
    height: 50px;
}
.mtk{
    display: none;
}